1. Field of the Invention
This invention relates to a structure of a cylinder head cover for an internal combustion engine, and more particularly, to an oil sealing structure of the cylinder head cover mounting portion in an engine having a plug tube for inserting an ignition plug.
2. Description of the Related Art
In an internal combustion engine for motor vehicles in the prior art, a problem has arisen in that lubricant oil is heavily dispersed in a cylinder head cover, and this sometimes causes an oil leakage from a fastening portion of the cylinder head cover to occur, due to various requirements such as a high speed and high performance. A problem has also arisen, especially in an overhead camshaft type engine, that noise is transmitted from the cylinder head cover. Therefore, a sealing gasket is conventionally disposed on a surface abutting between the cylinder head cover and a cylinder head so that the gasket provides a surface sealing by fastening the cylinder head cover to the cylinder head so as to give a uniform pressure to the abutting surface.
In a known art for mounting a cylinder head cover on a cylinder head, a structure is disclosed in which several stud bolts are fixed on the upper surface of the cylinder head so that the cylinder head cover can be rigidly mounted on the cylinder head by tightening several nuts on the corresponding stud bolts, as described in, for example, Japanese Unexamined Utility Model publication No. 54-31716. Another structure is also known in which a cylinder head cover is supported by a rocker support member, as disclosed in, for instance, Japanese Unexamined Utility Model publication No. 53-153107. In an engine having a plug tube, it is also known that a sealing packing is disposed between the plug tube and a cylinder head cover, as disclosed in U.S. Pat. No. 3,144,013.
The applicant (or assignee) of this invention has proposed in earlier filed applications that, in an engine having a plug tube, the sealing characteristics between the plug tube and a cylinder head cover can be improved (Japanese Utility Model application No. 59-54676), and that the fastening and sealing of a cylinder head cover can also be improved (Japanese Utility Model application No. 59-108171).